The institution directing this Bioengineering Research Partnership is the Loma Linda University (Neurosurgery Center for Research, Training and Education, Departments of Molecular Biology and Molecular Genetics, Biochemistry, Radiology, Radiobiology, Internal Medicine, Psychiatry and Pathology). Partners include BioErgonomics, Inc., St Paul, MN and the MRI Institute for Biomedical Research, St. Louis, MO. The goal of our multidisciplinary Bioengineering Research Partnership is to define the role of altered brain iron metabolism as a risk factor for Alzheimer's Disease in the in the context of elderly MCI patients. The engineering focus of the study is: (I) defining ex vivo markers in peripheral blood cells indicating iron or amyloid perturbations and (2) the development of a new magnetic resonance imaging (MRI) technology to quantitate and differentiate brain iron. Study subjects will be 75 patients (50 years of age or older) with minimal cognitive impairment who will be followed longitudinally for a three to four year period with sequential psychometric tests, special MRI sequences, and peripheral blood cell studies. Control subjects will consist of 25 healthy age-matched individuals who will be subjected to the same tests as the MCI group. A genetically engineered mouse with an iron regulatory protein 2 "knockout" that accumulates abnormal quantities of brain iron and displays a neurodegenerative disorder will be used to validate our new technology. A search for polymorphisms in the IRP-2 gene will be part of each patient's evaluation. At four years of serial follow-up it is anticipated that about 15% of the 75 study subjects will have AD, and correlations of psychometric data, brain iron localization and quantitation, as well as immunocytochemical peripheral blood will be established using statistical consultation and autopsy information if available.